Preheat the oven to 350 degrees F.
Grease a 9”x5” loaf pan with baking spray and line it with parchment paper, allowing excess paper to overhang the sides of the pan so it can easily be lifted out.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and pumpkin pie spice. Set aside.
In a large bowl using a handheld electric mixer (or stand mixer fitted with a paddle attachment), beat the softened butter with granulated sugar and brown sugar for 3 minutes.
Scrape down the sides of the bowl and add the oil, canned pumpkin puree, eggs, vanilla extract, and whole milk.
Beat for about 30 seconds or until everything is combined.
Carefully add the dry ingredients to the wet ingredients and mix together on a medium speed (or simply with a rubber spatula), scraping down the sides of the bowl as needed. Only mix until all the ingredients are just combined; overmixing can result in a dense cake.
Transfer the pumpkin cake batter into the prepared loaf pan and smooth into an even layer.
Run a knife down the center of the batter to create a line. This will help the loaf cake rise evenly and have a perfect loaf crack down the center, rather than being lopsided and random.
Bake the cake in the center rack of the oven for 55-65 minutes, making sure a toothpick comes out clean to ensure that it's fully baked.
Place the cake pan onto a wire cooling rack and allow it to cool for 30 minutes before using the parchment paper overhang to remove the cake from the pan.
Allow the cake to cool on the wire rack for at least 1-2 hours (if possible) before icing or serving.